Abstract :
An experiment was designed to determine the effect of forage species on growth rate and
gastrointestinal nematode infection in lambs. Southdown lambs (n = 20; 26±4.28 kg initial
BW) stratified by weight, sex and FAMACHA©score were assigned to graze either bermudagrass
[BG; Cynodon dactylon (L.) Pers.] or chicory [CH; Cichorium intybus L.]. Lambs grazed for
80 d from July 7, 2009 to September 25, 2009. Lambs were weighed and FAMACHA©scored
every 14 d. Fecal samples were taken on d 14, 42, 56, and 69 for modified McMaster fecal
egg counts. Ultrasound measures of subcutaneous fat thickness (FT) over the 12th and 13th
rib and longissimus dorsi muscle depth (MD) were taken on d 80. Lambs grazing CH had
lower (P < 0.01) FAMACHA©scores by d 69 than lambs grazing BG (2.4±0.43 and 3.1±0.59,
respectively). By d 80 FAMACHA©scores were 2.0±0.22 and 3.9±0.64 (P < 0.01) for CH and
BG, respectively and fewer (P < 0.01) CH lambs than BG lambs required anthelmintic treatment
(0/10 and 7/10, respectively). CH lambs also exhibited lower (P < 0.01) FEC than BG
lambs. Average daily gain was greater (P < 0.01) in lambs grazing CH than those grazing BG
(0.28±0.04 and 0.08±0.02 kg/d, respectively). At the end of 80 d, weights were 49.2±3.53
and 33.1±3.82 kg (P<0.01) for CH and BG, respectively. On d 80, FT and MD were greater
in CH lambs than those grazing BG (P < 0.01). Lambs grazing CH had increased performance
and reduced GIN infection compared to those grazing BG.
